The invention relates to a mounting for an opening roller of an open-end spinning machine comprising a plurality of teeth which are arranged, one behind the other, in a plurality of rows extending in circumferential direction, the tooth faces and tooth backs inclined in rotational direction, whereby in the area of the tooth tip, the tooth back is more inclined in relation to the radial plane than at the tooth base, and the tooth face forms an angle between 10.degree. and 30.degree. to the radial.
Usually, opening rollers are provided with a mounting of teeth or needles to comb out fibers from a fed sliver, which fibers are then spun into a yarn. The teeth are usually arranged on the opening roller in a plurality of rows extending in circumferential direction and at a distance to one another, with grooves being formed between the rows. The rows can be arranged in helical fashion, in waves or diagonally in circumferential direction, or in other ways on the circumferential side of the opening roller.
Due to their contour, the teeth are suitable for combing out single fibers from the sliver as soon as the fibers are released from the nipping line of the fiber feeding device. Most of the combed fibers are transported within the grooves formed by the rows of teeth and are brought by the rotating opening roller to a fiber feed channel. Due to the suction present in the fiber feed channel, and to the centrifugal forces created by the opening roller, the fibers are released from the mounting and fed by means of the fiber feed channel to a spinning element.
A mounting for an opening roller is known in U.S. Pat. No. 5 4,646,389. The teeth of the mounting are arranged in circumferential direction, one behind the other, in such a way that a plurality of rows are formed with grooves between the rows. The tooth faces are inclined at an angle between 12.degree. and 30.degree. in rotational direction. The tooth backs are also inclined in rotational direction, whereby the angle of inclination from the tooth tip to the tooth foot diminishes gradually.
The teeth are aggressive enough in this form to comb the fibers out of the sliver, without the re-release of the combed fibers being hindered thereby. The contour of the teeth ensures a good taking-along of the fibers in the grooves formed between the rows of teeth.
It is an object of the present invention to improve the transport of the fibers.
This object has been achieved in accordance with the present invention in that the tooth back is inclined at the tooth tip at an angle to the radial plane, the side of which angle intersects the tooth face of the following tooth at an intersecting point which is at least one fifth of the tooth height away from the tooth tip and from the tooth base.
As a result of the inclination of the tooth back according to the invention, the contour of the tooth, in particular in the area bordering the tooth tip, is altered. The steeper inclination, in contrast to that of the known tooth, leads to an enlargement of the tooth flanks and thus to an increased frictional effect on the fibers inside the grooves. Thus the combed fibers are better transported.
The inclination is, however, on the other hand not that steep that the required aggressiveness of the tooth needed for effective combing out is lost. The steeper inclination of the tooth back does not hinder the release of the transported fibers after they have been combed out. A practical compromise between the technically desired effects of combing out, taking along and releasing of the fibers is maintained.
Under the term "mounting" is understood the entire profiled outer circumferential surface of an opening roller including all elevations and hollows. Included in the mounting are all rows of teeth, grooves, notches and other profiling irrespective of how they are made. It is irrelevant whether the mounting is made, for example, by mounting a saw tooth wire onto a cylindrical circumferential surface or by working the teeth into the material of a cylindrical or hollow cylindrical body.
In an advantageous embodiment of the present invention, the distance between the tooth face and tooth back, that is the width of the tooth flank, is between 0.5 to 1.4 times that of the tooth height. The distance is measured at the start of the second fifth of the tooth height, that is at a point which is a fifth of the tooth height away from the tooth base. In the case of the above mentioned advantageous ratio of tooth width to tooth height, the contour and the size of the tooth flanks are set in such a way that the above mentioned technical effects can be brought about in an improved way.
In a further advantageous feature of preferred embodiments, the teeth are arranged in a spacing which is 0.8 to 1.6 times the height of a tooth. The inclination of the tooth back according to the invention has a positive effect on the taking-along of the fibers, in particular when the ratio of the spacing to the tooth height is relatively small.
In advantageous embodiments, the tooth back graduates at the tooth base through a curve into the tooth face of the following tooth. The curve ensures that the fibers do not land in the area of the tooth base after being combed out. The fibers lying in the grooves located above the tooth bases are taken along in an advantageous way as a result of the tooth form according to the invention.
In a practical embodiment, the distance between the tooth back of one tooth and the tooth face of the following tooth measures 0.6 to 1.2 times the distance between the tooth back and the tooth face of one single tooth. The distances are based on the measurement at the start of the second fifth of the tooth height, measured from the tooth base. The former distances determine the size of the axial notch, located between two teeth, as well as the position of the tooth face relative to the tooth back of the preceding tooth. The resulting form and arrangement of the teeth leads to a further improvement in the taking along of the fibers.
It is advantageous when the angle formed at the tooth tip between the tooth back and the radial plane measures between 35.degree. and 70.degree. .
It is further practical when the angle at the tooth tip formed between the tooth back and the tooth face measures between 25.degree. and 60.degree.
In an advantageous embodiment, the tooth face has a concavely curved section. This construction prevents the fibers all reaching the area of the tooth base after being combed out. This applies in particular when in addition, the tooth back graduates at the tooth base through a curve into the tooth face of the next tooth. As a result of the tooth form according to the present invention, the fibers in the grooves located above the tooth bases are effectively taken along.
In a practical embodiment, the tooth back has a hump, adjacent to which is a section inclined more to the radial plane towards the tooth tip, and a section inclined less no the radial plane towards the tooth base. This construction enables the angle of inclination at the tooth tip to be made sufficiently small so that the combing out effect is not impaired. Thus, in the case of a narrower spacing between the teeth, a sufficiently large tooth surface can be maintained at the tooth flank.
It is advantageous when the section with the large angle of inclination and/or the section with the smaller angle of inclination, extend at least partly straight.
In an advantageous embodiment, the hump comprises a convexly curved section, in which the section with the larger angle of inclination graduates into the section with the smaller angle of inclination.
These and further objects, features and advantages of the present invention will become more readily apparent from the following detailed description thereof when taken in conjunction with the accompanying drawings.